sustain vs sustainment

sustain is not a noun while sustainment is a noun.

Word	Noun	Adjective	Verb	Adverb
sustain	No	No	Yes	No
sustainment	Yes	No	No	No

sustain (noun)	sustainment (noun)
	the act of sustaining life by food or providing a means of subsistence

sustain (verb)	sustainment (verb)
undergo (as of injuries and illnesses)
establish or strengthen as with new evidence or facts
admit as valid
supply with necessities and support
provide with nourishment
be the physical support of; carry the weight of
lengthen or extend in duration or space